The present invention relates to a machine for conditioning, i.e., making packets of cigarettes.
Packets of cigarettes normally comprise a group of cigarettes packed in packing material and containing a given number of cigarettes arranged in layers, and conditioning machines for producing such packets comprise a first portion in which the cigarettes are arranged into groups divided into layers, a second portion in which the groups are packed in packing material secured by an adhesive substance, and a third portion in which the packets are fed into respective pockets, each of which provides for snugly housing and maintaining a desired shape of the packet as the packet is fed along a drying path to allow the adhesive substance to set.
The first portion comprises a hopper having at least one outlet with substantially vertical channels, down which the cigarettes are fed under their own weight and that of the cigarettes on top; and means for extracting a group or layer from the outlet and feeding the group or layer onto a feed conveyor for supplying a succession of packing wheels, which form part of said second portion, and which provide for both forming and feeding the packets to a drying conveyor forming part of said third portion.
In response to increasing demand for higher-output conditioning machines, technical solutions are continually being devised to increase the traveling speed of the conveyors and the speed at which the groups and packets are transferred between adjacent conveyors. Particularly effective in increasing the output of conditioning machines has been the adoption of continuously-moving conveyors as opposed to conventional step-operated types. Continuously-moving conveyors have proved particularly effective when applied to said second portion of the machine, and have enabled a substantial increase in the traveling speed of the packets and cigarettes, while at the same time preventing the packets or cigarettes from being damaged. For this reason, the second portion of the conditioning machine is often referred to as the fast portion, and the first and third portions--in which continuously-moving conveyors have proved less effective--as the slow portions. The slowness of the first portion is a consequence of the physical limitations of the cigarettes, which are fed down the channels under their own weight, and of the fact that any attempt to accelerate the downward travel of the cigarettes results in damage, such as tobacco fallout from the ends and bending, if not actual breakage, of the cigarettes. The slowness of the third portion, on the other hand, is a consequence of the time taken by the adhesive substance to dry, and which is allowed by feeding the packets slowly along a path of given length. On the other hand, reducing drying time using heaters to set the adhesive substance faster would only result in rapid surface drying of the substance, in delayed drying of the central portion of the substance, and, therefore, in an increase in overall drying time.
Consequently, machine output has been increased by increasing the number of hopper outlets and the length of the drying paths cooperating with the fast portion. Patent DE 3,046,065, for example, relates to a conditioning machine comprising a first portion with two hopper outlets for simultaneously forming two groups of cigarettes, which are fed, in the second portion, to a drum comprising equally spaced pockets, and which is operated in steps twice as long as the spacing of the pockets. The drum, in turn, feeds the groups to a packing line defined by further drums, which feed the finished packets along a single packing path to two drying drums defining respective parallel drying paths. In other words, the machine described comprises a fast portion defined by the step-operated drums, but which are operated in steps twice as long as the spacing of the pockets, and two slow portions: the first portion featuring two outlets, i.e. two group-forming lines; and the third portion defined by two drying drums, i.e. two drying lines or paths.
The adoption of continuous packing lines has called for a further increase in the number of slow-portion lines, which, however, over and above a given number, seriously complicate the conditioning machine as a whole. On the other hand, limiting the number of drying lines calls for fairly long drying paths, thus increasing the length and size of the machine.